Effects of potential probiotic Bacillus cereus EN25 on growth, immunity and disease resistance of juvenile sea cucumber Apostichopus japonicus

This study was conducted to determine effects of potential probiotic Bacillus cereus EN25 (isolated from mud of sea cucumber culturing water bodies) on growth, immunity and disease resistance against Vibrio splendidus infection in juvenile sea cucumbers Apostichopus japonicus. Animals were respectively fed diets with B. cereus EN25 at 0 (control), 105, 107 and 109 CFU/g for 30 days. Results showed that dietary B. cereus EN25 had no significant effects on growth, total coelomocytes counts and acid phosphatase activity of A. japonicus (P > 0.05). Dietary EN25 at 107 CFU/g had significantly improved the phagocytosis, respiratory burst activity and total nitric oxide synthase activity of animals (P < 0.05). Compared to control, dietary EN25 at 105 or 107 CFU/g had no significant effects on superoxide dismutase activity of A. japonicus (P > 0.05), whereas dietary EN25 at 109 CFU/g had significantly decreased its activity (P < 0.05). The cumulative mortality after V. splendidus challenge decreased significantly in sea cucumbers fed with EN25 at 107 CFU/g (P < 0.05). The present study confirmed dietary B. cereus EN25 at 107 CFU/g could significantly improve immunity and disease resistance in juvenile A. japonicus.